Method of making nonwoven stitch-reinforced fabric

ABSTRACT

An improved method of making a nonwoven fabric reinforced by stitching wherein a web or batting made of a multiplicity of substantially parallel fibers is reinforced by stitching yarn and is then stretched in a direction parallel to the substantially parallel fibers whereby to greatly improve the surface characteristics of the cloth. The fabric is especially useful as a backing for a polymeric coating in making simulated leather products, outerwear and the like.

United States Patent Inventor Leslie E. Williams East Point, Ga.

Appl. No. 842,619

Filed July 17, 1969 Patented Aug. 31, 1971 Assignee Unlroyal, Inc.

New York, N.Y.

METHOD OF MAKING NONWOVEN STITCH- REINFORCED FABRIC 6 Claims, 6 Drawing Figs.

Int. Cl. Field of Search [56] References Cited UNITED STATES PATENTS 520,400 5/1894 Cattlow 28/77 2,539,301 l/l95l Foster.... 28/72X 3,365,918 l/l968 Hughes 66/85 X FOREIGN PATENTS 884,427 12/1961 Great Britain 28/77 Primary Examiner-Louis K. Rimrodt Attorney-David B. Miller ABSTRACT: An improved method of making a nonwoven fabric reinforced by stitching wherein a web or batting made of a multiplicity of substantially parallel fibers is reinforced by stitching yarn and is then stretched in a direction parallel to the substantially parallel fibers whereby to greatly improve the surface characteristics of the cloth. The fabric is especially useful as a backing for a polymeric coating in making simulated leather products, outerwear and the like.

METHOD UT MAKING NONVJOVEN STI'lItIH= REINFORCED lFAhhlllC BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to nonwoven cloth fabrics and especially to nonwoven cloth fabrics made of a multiplicity of sub- SUMMARY OF THE INVENTION A web or batting made of a multiplicity of fibers which are preferably, although not necessarily, parallel, are reinforced by stitching which is placed in the web or batting by either a sewing machine or a knitting machine. An example of a highly useful machine for implanting the reinforcement stitching is the knitting or stitching machine known as Elitex-Arachne machine. Preferably the stitches are formed so that on one side they are in the form of tricot stitching whereas on the other side they will inherently appear as chain stitching.

After the fabric has been reinforced as described it is placed on a tentering machine for stretching in the direction that the fibers run, whereby to greatly improve the surface characteristics of the reinforced nonwoven fabric. In the present contemplated use of the invention the fabric thereafter is coated with a polymeric coating.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a plan view of a portion of a fiber web or batting useful in the present invention;

FIG. 2 is a view similar to FIG. I with the batting reinforced by stitching perpendicular to the direction of the fibers;

FIG. 3 is a view similar to FIG. 2 showing the opposite surface of the fabric;

FIG. 3 is a sectional view taken along the line llof FIG. 2;

FIG. 5 is a view similar to FIG. 4 showing the reinforced web or batting after tentering; and

FIG. 6 is a view similar to FIGS. 4 and 5 showing the fabric after coating with a polymer.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings in detail, the production of nonwoven fabrics from webs or battings of fibers has been known for many years. Such webs or batting may be in the form of random unspun fibers or, as shown in FIG. I, in the form of substantially parallel unspun fibers. The batting 110 of FIG. I with substantially parallel fibers is preferred in the present process, although the fiber parallelism is not essential thereto. The fibers from which the batting I0 is made may be natural fibers or synthetic fibers of any type, although long fibers are preferable in that they yield a stronger end product. In fact, a most desirablefiber is a monofilament fiber ofsub-. stantially infinite length as, for example, tow made of nylon, polyester, rayon or acetate, or any othersynthetic fiber that is extruded from a spinerette. While from a cost factor spun yarns are not desirable to the present invention, from a viewpoint of operability spun yarns can be substituted for the unspun fibers in the web I0.

After producing the web or batting lb of FIG. i, it is reinforced and integrated. This is accomplished by stitching generally running transversely of the direction of the fibers in the batting Iltl. Such stitching is designated by the reference numeral The stitching may be of the type done by knitting machines, sewing machines, tufting machines, quilting machines or the like. The term stitching as used herein is in tended to cover all such and similar forms of yarn implantation. Desirabiy, the stitching, in addition to having a main component running transversely of the fibers, has a component extending in a direction parallel to (or at an acute angle to) the fibers, whereby to provide for reinforcement in the direction of the fibers as well as in the direction transverse thereto. Accordingly, a most desirable stitch for reinforcing the web or batting i0 is a tricot stitch whichaigzags on one surface of the batting and appears as a straight chain stitch on the opposite surface thereof. In FIG. 3 the surface showing the zigzag stitch may be seen and in FIG. 22 the opposite surface showing the chain stitch may be seen.

However, it should be borne in mind that while the illus trated form of stitch reinforcement is presently preferred, other forms of stitching may be employed. Thus, for example, a straight chain stitch on both sides may be employed. Alternatively, in lieu of the tricot stitch, a crossover stitch may be employed, which crossover stitch also has a zigzag component on one side and a chain stitch on the other. Other forms of zigzag stitching are also useful in connection with the present invention. In addition, combinations of chain and tricot stitching may be employed.

It is presently preferred that the stitching on the web or batting ill be performed on the Elitex-Arachne knitting machine which is described and claimed in a number of patents such as, for example, US. Pat. Nos. 3,079,778; 3,310,964; and 3,309,901. These patents and others are embodied in the Elitek-firrachne machine as described in the present Elites brochure on the machine. Machines manufactured by other manufacturers and having similar characteristics are the Maliwatt and ACl-lll l Mark IV machines which may be employed in performing the present method. The particular machinery used does not form a part of the present invention and various modifications of equipment will readily suggest themselves to persons skilled in the art. Even a conventional sewing machine can be employed as could quilting machines and the like to stitch in the reinforcement yarn as already described.

As already pointed out, the type of fiber to be employed in the web or batting It is a matter of choice and depends upon the proposed end use of the material being made. Thus, natural such as cotton, flax, wool and silk may be employed, and synthetic fibers such as nylon, rayon, acetate, polyester, acrylic, polyolefrn, etc. may be employed. inorganic fibers such as fiberglass and asbestos may be also be used. The fiber density is a matter of choice well within the skill of the art.

With respect to the stitching, the number of stitches per inch and the number of stitch rows per inch are parameters which the skilled art worker may select in accordance with the particular application. The type of fiber from which the stitch yarn is made is a matter of choice, well within the ability of the skilled art worker and may be any of the fibers previously mentioned with respect to the unspun fibrous content of the batting 110. Not only the composition of the stitch yarn but its physical properties are a matter of design selection and choice. Suffice it to say'the same considerations as the skilled art worker brings to bear in selecting the components and parameters for standard stitch reinforced nonwoven fabrics as illustrated in FIGS. 2, 3 and l, are brought to bear when deciding upon the components and parameters of such fabrics for use in practicing the present method. Suffice it to say with regard to the stitching that generallythe number of stitches per inch ranges from about four to about 24 or 25, and the number of stitch rows per inch may vary from about four to about 22. It has been found that an increase in either or both of these tends to reduce the ability of the material to be as on a device similar to a curtain stretcher.

stretched. To date the best results have been obtained in the midrange for the number of stitches per inch and for the number of stitch rows per inch. Very desirable results have been achieved with 12 stitches per inch and about 12% stitch rows per inch.

The reinforced web or batting is designated by the reference numeral 16 and is shown in cross section in FIG. 4. It will be seen that such a product, which is well known, has an uneven or ribbed surface characteristic due to the fact that the batting is compressed at the points where the reinforcement stitching 12 passes therethrough. This gives a ridged or ribbed effect and it is this effect that has caused significant problems in utilizing the product 16 in the manufacture of polymericcoated fabrics. Thus, when such a fabric is coated with any suitable polymeric coating, there is a tendency, due to the unevenness of the surface 18, for the fabric surface to show through the polymeric coating and yield a clothy appearance which is undesirable and unwanted in many applications. It is this clothy surface quality which the present method is designed to reduce or eliminate. to the Worcester, machine, Germany. botli have with the from a v iewpoi nt To improve the surface quality of the reinforced fabric 16, the fabric is stretched in the direction transverse to the stitching 12. Thus, where the fibers are oriented substantially parallel to one another, the stretching is done in a direction parallel to the fibers. The stretching can be performed on any suitable apparatus. For, example, well-known types of tentering machines as exemplified by the Famatex high-production, single-layer tenter, Type PRH 30, manufactured by the Famatex Company of West Germany and sold in the United States by the David Gessner Company of Worcester, Mass. may be and has been employed. Other suitable tentering machines are the Krantz DZ tentering machine manufactured by H. Krantz Appreturmaschinen-Fabrik, of Aachen, West Germany. Numerous other tenteringmachines may be employed. Moreover, in performing the present method it is of no consequence that the tentering machine be of the pin type or the clip type, as both have been employed in connection with the present invention with equal facility and success. While, from a viewpoint of production capacity, tentering machines of the type already mentioned are highly desirable, it will be recognized that the stretching step in the present method may be performed on other forms of stretching apparatus such as, for example, expander rolls, or mechanical pullers. While it is probably not practical from a production viewpoint, the stretching could even be performed manually The amount of stretch which can be imparted to the stitched web 16 is wholly dependent upon the composition of that stitched web. Thus the nature of the fiber and the nature of the stitch yarn has a significant bearing on the amount of stretch that can be tolerated. In addition, the type of stitch and the number of stitches per inch and the number of stitch rows per inch afi'ects the stretchability of the material. The density of the nonwoven web also has a significant bearing on the stretchability. However, once the skilled art worker is informed that a stitch reinforced web 16 can be stretched, the amount of stretch which can be imparted to any particular stitch-reinforced web 16 is something that can be worked out by the skilled art worker with relative ease and rapidity and is dependent mainly upon the particular reinforced web that he iys rhsrtsescisssf thsrs ar iasna sa k,

Percent stretch 0 10. 2 18. 4 22. 4 28. 6 32. 7

Weight (ozsJsq. yd.) 3.19 3.13 3.11 2.96 2.85 2. 62 Width finches)---" 49 54 58 60 63 65 Gauge (thickness in inches 0. 0243 0. 0241 0. 0227 0.0210 0. 0208 0. 0193 arp 7. 7 7.0 6. 7 7.0 7.0 6. 0 Fill 5.4 4.7 4.9 4.9 6.1 4.9 Stretch at break (percent):

Warp (lengthwise) 28. 46 38. 74 27. 46 26. 53 35. 40 33. 07 Fill (crosswise) 198. 60 173. 67 161. 22 177. 47 155. 27 144. 07 Ford stretch (10# wt.):

Warp 17. 32 31. 83 18. 67 23. 66 40. 17 28. 99 Fill 118.33 70. 00 89. 99 77. 33 60. 17 82. 99 Ford set (percent):

Warp (lengthwise) 4.16 12. 83 6.33 8. 33 18. 67 9. 33 Fill (crcsswise) 103. 33 60. 00 76.50 67. 49 53. 33 70. 49 Stitches/inch Warp- 13 13 13 13 13 13 Stitches rows/inch 12. 5 12. 0 12. 0 11. 2 10.8 9. 9

NOTE: All examples showed significant improvement in surface quality over the starting fabric.

Uponthe stretching step being eridriirehfifiEii significant improvement in the surface quality of the fabric 16. Thus the ridges or ribs 14 which appear in FIG. 4 are radically reduced in prominence to yield a far smoother surface on both sides of the tentered fabric 20 when compared with the untentered fabric 16. Thus significant gain in surface quality, along with an increase in the square yardage of material obtained over that produced .without the stretching step, makes the fabric extremely desirable, especially in connection with any applications where polymeric coatings are to be applied thereto as, for example, to manufactured simulated leathers or plastic outerwear or the like. It is well known that suitable coatings on cloth fabrics can be made from vinyl, polyurethane, and natural and synthetic rubbers. Other polymeric coatings will suggest themselves to the skilled art worker.

Thus when a polymeric coating 22 is applied to the fabric 20 in a normal and well known manner, as by calendaring or casting viscous polymeric materials on to a surface of the fabric 20, by virtue of the comparative smoothness of the stretched fabric 20 when compared with the unstretched fabric 16, clearly there is a significant reduction in likelihood of the fabric 20 showing through the polymeric coating 22 (FIG. 6), to yield a clothy appearance. As the clothy appearance is, for many applications, undesirable, a significant improvement is achieved by the present method. Incidentally, while attaining this desirable improvement in the surface quality of the, unwoven cloth or fabric, a significant gain in the quantity of fabric is achieved whereby to render the method highly desirable from an economic viewpoint.

What I claim is: I 1. A method of making an improved nonwoven stitch reinforced fabric, comprising the steps of taking a nonwoven fibrous batting having a plurality of substantially parallel rows of reinforcement stitchings thereon,

and stretching said stitch-reinforced fibrous batting to permanently elongate the same in a direction transversely of said rows to thereby improve the surface quality of the stitch-reinforced fabric.

2. The method of claim 1, wherein the fibers of said nonwoven fibrous batting are oriented substantially parallel to each other, and said stitch rows extend transversely of the extent of said fibers.

3. The method of claim 2, wherein the stitches forming said stitch rows have portions in the plane of said batting which extend transversely of the direction of extent of said rows.

4. The method of claim 2, wherein said rows of stitching extend perpendicular to said fibers of said batting.

5. The method of claim 4, wherein the stitches forming said stitch rows have portions in the plane of said batting which extend transversely of the direction of extent of said rows.

6. The method of claim 5, further comprising the step of coating a surface of said stretched batting with a polymeric coating. 

2. The method of claim 1, wherein the fibers of said nonwoven fibrous batting are oriented substantially parallel to each other, and said stitch rows extend transversely of the extent of said fibers.
 3. The method of claim 2, wherein the stitches forming said stitch rows have portions in the plane of said batting which extend transversely of the direction of extent of said rows.
 4. The method of claim 2, wherein said rows of stitching extend perpendicular to said fibers of said batting.
 5. The method of claim 4, wherein the stitches forming said stitch rows have portions in the plane of said batting which extend transversely of the direction of extent of said rows.
 6. The method of claim 5, further comprising the step of coating a surface of said stretched batting with a polymeric coaTing. 